1. Field of the Invention
The present invention concerns simultaneous rotation and reciprocation of well pipe and, more particularly, clamp-on apparatus for mechanically rotating and reciprocating well pipe during cementing operations.
2. Background Information
The simultaneous rotation and reciprocation of well pipe while cementing improves the quality of the cement job. At present, only hydraulic power swivels allow simultaneous rotation and reciprocation of well pipe. These hydraulic swivels stop rotation when a maximum torque limit is reached. They work well but are expensive and require an operator and an external power source, usually truck mounted, for their use. The present invention permits simultaneous rotation and reciprocation of well pipe using only rig power; pipe rotation stops automatically when a maximum torque limit is reached; and the apparatus is independent of the type of rig with which it is used and is easy to rig up and operate.